Guard for circular saws.



W. B. MARTIN.

GUARD FOR CIRCULAR SAWS.

APPLICATION FILED AUG. 20, 19131 Patented Jan. 19, 1915.

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W. B, MARTINQ GUARD FOR CIRCULAR SAWS.

APPLIGATION FILED AUG. 20, 1913.

Patented J an. 19, 1915.

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WALLACE B. MARTIN, OF ST. PAUL, MINNESOTA.

GUARD FOR CIRCULAR SAWS.

Application filed August 20, 1913.

To all whom it may concern Be it known that I, WALLACE B. MARTIN, acitizen of the United States, residing at St. Paul, in the county ofRamsey and State of Minnesota, have invented certain new and usefulImprovements in Guards for Circular Saws; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same.

My invention has for its object to provide an improved guard adapted foruse in connection with rotary cutting heads of various kinds ofmachines, but is especially designed for circular saws.

To the above ends, generally stated, the invention consists of the noveldevices and combinations of devices hereinafter described and defined inthe claims.

In the accompanying drawings, which illustrate the invention, likecharacters indicate like parts throughout the several views.

Referring to the drawings :-Figure 1 is a left side elevation of theimproved guard working in connection with a circular saw, some partsbeing broken away and some of the exposed parts being shown in section;Fig. 2 is a detail view partly in plan and partly in horizontal section,taken on the line m 00 of Fig. 1; Fig. 3 is a view partly in frontelevation and partly in vertical section, taken on the line 00 m of Fig.1; Fig. 4 is a right side elevation of the parts shown in Fig. 1, someparts being broken away; and Fig. 5 is a detail view partly in sideelevation and partly in vertical section taken on the line m m of Fig.3.

For the purpose of illustrating the im proved guard in working position,an ordinary circular saw 1 is mounted on a rotary power driven spindle 2and works upward through a slot in a work table 3 in the customarymanner. These parts may be of the standard or any desired construction.

Referring now to the improved guard, the same is in the form of a twopart hood comprising an arch plate 4 which extends over and on each sideof the saw 1 and a vertically extended guard plate 5 which coversSpecification of Letters Patent.

Patented J an. 19, 1915. Serial No. 785,706.

the left side of said saw. The arch plate 4: 1s provided with aplurality of transverse openings 5 through which the work may be viewedas the same is fed to the saw. lnte grally formed with the left handlongitudinal edge portion of the arch plate 4: is a vertically extendedflange 6 having, at its intermediate portion, an upwardly projectingextension 7 Integrally formed on the forward end of the arch plate 4 andflange 6 and laterally ofiset from the guard plate 5 is a horizontalextension 8. A segmental extension 9 is integrally formed with the rearend of the arch plate 4; and the flange 6 and is provided, on itsperiphery, with a plurality of wide ratchet teeth 10.

The guard plate 5 is in the form of a segment working against andparallel with the outer face of the flange 6 and with its horizontaledge extended parallel with the upper face of the work table 3. A washerequipped stud 11 is anchored to the arch plate flange 6 and worksthrough a segmental slot 12 formed in the guard plate 5 for holding saidguard plate in its proper relation. with respect to the arch plate 4:.The guard plate 5 is suspended with respect to the arch plate 4. forlimited vertical and endwise movements by a segmental lifting plate 13and a link 14.

The lifting plate 13 works vertically betweenthe guard plate 5 and theextension 8 and is pivotally secured to said extension, at its axis, bya nut equipped bolt 15, for limited swinging movement. A washer equippedstud 16 anchored to the extension 8 works through a segmental slot 17formed in the lifting plate 13 for holding said plate in proper positionwith respect to said extension. A nut equipped bolt 18 pivotallyconnects the lower outer edge portion of the lifting plate 13 to theguard plate 5 and a laterally projecting finger piece 19 is secured tothe opposite portion of said lifting plate 13, for raising said guardplate, at will. On the periphery of the lifting plate 13 is formed aplurality of ratchet teeth 20 and a cotiperating lock dog 21 ispivotally secured at 22 to the arch plate flange 6. This lock dog 21 isprovided with a laterally projecting finger piece 23 and a stopprojection 24 arranged to engage the arch plate flange 6, to supportsaid lock dog 21 in an inoperative position. As shown, the lifting plate13 has integrally formed with its lower oblique edge a laterallyprojecting cam flange 25 which is engaged by the board Z as the same isfed to the saw, to lift the guard plate 5 and permit said board to passthereunder.

The link 14 extends substantially parallel with a line throughconnections 15 and 18 of the lifting plate 13, and its lower end ispivotally secured, by a nut equipped bolt 26, to an upwardly projectingear 27 integrally formed with the rear peripheral edge of the guardplate 5. A nut equipped bolt 28, projecting through a longitudinallyextended slot 29 in the upper end of the link 14, pivotally connectssaid link to the rear upper portion of the extension 7. As willpresently appear, the purpose of the slot 29 is to permit a shorteningof the operative length of the link 14 between its pivotal connections26 and 28, by an endwise upward thrust thereon.

Integrally formed with the rear peripheral edge of the guard plate 5 isa laterally projecting flange 30 terminating, at its upper edge, in abevel tooth or pawl 31 for cooperation with the ratchet teeth 10, butnormally out of engagement therewith. A lock dog 32 is pivotally securedat 33 to the guard plate 5 for co'ciperation with the ratchet teeth 10.

The improved guard is suspended from a ceiling or overhead support Y forpendulum-like movement, transversely of the saw 1 by a depending hangershaft 34, as shown in the form of a pipe. This shaft 24 is provided, atits upper end, with a cap 35, pivotally secured by a bolt 36 to a socket37 which is rigidly secured to the ceiling by screws or other suitablemeans. A vertically adjustable head 38 is telescoped onto the lower endof the hanger shaft 34 and is secured in different adjustments thereonby a set screw 39 having screw threaded engagement with a boss on saidhead and with its inner end impinging against said hanger shaft.Integrally formed with the head 38, on one side thereof, is a sleeve 40which extends parallel with the opening through said head and ispreferably rectangular in cross section. Slidably mounted within thesleeve 40 is a bar 41, to the lower end of which the arch plate 4 ispivotally secured by a nut equipped bolt 42. This pivot bolt 42 extendsthrough the arch plate flange 6, substantially at its longitudinal andtrans Verse center, and its head is countersunk therein, out of the wayof the guard plate 5. Obviously, this pivotal connection 42 permitsangular rocking adjustment of the ends of the arch plate 4 toward andfrom the-saw 44 formed in the upper end portion of the extension 7, tosecure the arch plate 4 in different set adjustments transversely ofsaid bar. A hand set screw 45 has screw threaded engagement with thesleeve 40 and the inner end thereof impinges against the bar 41, tosupport said bar in difi'erent vertical adjustments with respect to saidsleeve 40. In cross section, the bar 41 is the same shape as thepassageway through the sleeve 40 and is held thereby against rotation.

The lower end of the hanger shaft 34 is rigidly held against lateralmovement longitudinally of the improved guard by a pair of upwardlydiverging cables 46, having attached to their upper ends hooks 47 thatare secured to the ceiling Y by eyes 48. To the lower ends of each cable46 is secured a comparatively long screw threaded eye bolt 49, attachedto one end of a turn buckle 50 by a pair of opposing clamping thumb nuts51. In the other end of each of these turn buckles 50 is swiveled a hook52. These hooks 52 are detachably secured to a pair of opposite andhorizontally projecting ears 53 formed, respectively, with the upperends of the head 38 and the sleeve 40. Obviously, the cables 46 permitswinging movement of the hanger shaft 34 transversely of the saw 1.

For securing the hanger shaft 34 against oscillatory movement, while thedevice is in an operative position, a cable 54 is anchored, at its ends,to eyes 55 secured to the ceiling Y on opposite sides of the hangershaft 34 and in a direct line with the swinging movement of said hangershaft. The depending intermediate portion of the cable 54 is adj ustablysecured to the head 38 by a depending lever 56, detachably fulcrumed, atits upper end, to a relatively wide downwardly projecting hook lug 57which is integrally formed on the lower end of the head 38 opposite fromthe-sleeve 40. As shown, the fulcrumed end of the lever 56 is bifurcatedand the prongs thereof embrace the sides of the hook lug 57 and holdsaid lever against edgewise movement. The cable 54 is frictiouallyclamped in different longitudinal adjustments on the inner face of thelever 56 by a thumb nut equipped bolt 58. This bolt is passed throughthe intermediate portion of the lever 56, and its head is arranged toengage the cable 54 and clamp the same onto said lever. The lever 56 ispositively locked to the head 38 in an operative position by a screwthreaded stud 59, integrally formed with the lever 56 between itsfulcrumed end and the bolt 58. This stud 59 works between the prongs ofa depending bifurcated lug 60, integrally formed with the head 38immediately below the hook 57. The screw stud 59 is provided with athumb nut 61 arranged to engage the inner face of the lug 60 as a baseof resistance and draw the lever 56 into a locked position against theouter face of said lug. As best shown in Figs. 1 and 5, the pull of thecable 54 on the lever 56 is past a dead center and thus independent ofthe thumb nut 61 and stud 59.

Interposed in the left hand section of the cable 54, with respect toFig.3, is a short chain 62 attached, at its lower end, to the main sectionof the cable 54 and adjustably secured, at its other end, to a hook 63attached to the short or upper section of the cable 54. Obviously, byinserting the hook j 63 in difierent links of the chain 62, the desiredtension may be placed on the cable 54.

Pivotally secured at 64 to the rear end of the guard plate 5 is adepending double toothed dog which prevents any tendency of the boardbeing sawed to kick back. The free or toothed end of this dog 65normally rides over the upper surface of the board Z.

The operation and difierent adjustments of the improved guard may bebriefly described as follows: By longitudinally adjusting the bar 41 inthe sleeve 40, the arch plate 4 may be secured in a position to supportthe guard plate 5, when in its normal or lowermost position, withitslower longitudinal edge parallel with but just out of contact withthe upper face of the saw table 8. The clamping bolt 43 and slot 44 inthe extension 7 permit the arch plate 4 to be set in different angularadjustments with respect to the table top, in order that the lowerlongitudinal edge of the suspended guard plate 5 may be properlyadjusted with respect to said table top. The cables 46 rigidly hold thearch plate 4 against endwise movement and the cable 54and lever 56rigidly hold the arch plate 4 against lateral movement and also permitthe said arch plate to be secured in its proper relation over the saw 1.By releasing the lever 56 from the head 88, the entire device is freefor swinging movement, so that the same may be moved to and fromoperative positions. Then in an inoperative position the entire deviceextends in an oblique position, as indicated by dotted lines in Fig. 3,and may be supported in this position by securing one of the cables 46over the hook 63. To release the lever 56 from engagement with the hook57, it is first necessary to loosen the thumb nut 61 i sufficiently topermit the stud 59 to move out from between the prongs of the bifurcatedlug 60. Then, by -moving the free or long end of the lever 56 upward,the same may be moved out of engagement with the hook 57, therebyleaving the improved guard free forswinging movement.

In feeding the board Z to the saw, the forward end thereof first engagesthe cam flange 25, thus rocking the lifting plate 13 on its pivot 15. Itis highly important to note that the cam flange 25 and link 14 inclinerearwardly and downwardly and, as the same are lifted during themovement of the board Z, the guard plate 5 recedes in the direction ofmovement of the board, as the same is fed to the saw, and at the sametime is raised. This receding movement of the guard plate 5, during itslifting movement, is very important for the reason that it takes verylittle power to lift said guard plate a sufficient distance to permitthe board Z to pass thereunder. After the board Z has passed from underthe guard plate 5, the same again immediately returns to its normalposition, under the action of gravity.

In case a number of boards of the same thickness are to be sawed, thelock dog 21 may be turned into engagement with the ratchet teeth 20, andthe first board passing under the guard plate 5 will raise the same tothe required height. After this board has passed from under the guardplate 5, the dog 21 will hold the guard plate 5 against return movementso that it will not be neces sary to lift the guard plate 5 during thesawing of the remaining boards. In case a thicker board is fed to thesaw, the lock dog 21 will slip over the ratchet teeth 20, therebypermitting the guard plate 5 to move to the required height.

In case it is desirable to lock the guard plate 5 in a pre-determinedraised position and against either upward or downward movements, boththe lock dogs 21 and 32 are moved, respectively, into engagement withthe ratchet teeth 20 and 10. When the lock dog 32 is in engagement withthe ratchet teeth 10, the rear end of the guard plate is positively heldagainst upward movement, and thereby prevents any kick-back of theboards being fed to the saw. The causes of the so-called kick-backs arewell known and also the dangers of the same. When the lock dog 32 is outof engegement with the ratchet teeth 10, the tooth 31 will automaticallyengage the ratchet teeth 10 by a slight forward lifting movement of therear end of the guard plate 5. This movement of the guard plate will putan end thrust on the link 14 and the slot 29 formed therein will permitsuflicient shortening of the operative length of said link to allow thetooth 31 to be carried into engagement with the ratchet teeth 10,thereby positively locking the rear end of said guard plate 5 againstupward movement caused by the lifting of the board Z from the table 3.

connections supporting said guard plate from said arch plate forvertical movement and a receding movement in the direction of movementof the work as the same is fed to the saw, and automatic means,operative under a lifting movement of said guard plate, for locking thesame against upward movement.

2. A guard of the kind described comprising a hood made up of arelatively fixed arch plate and a relatively movable guard plate,connections, including a lifting plate, supporting said guard plate fromsaid arch plate,'for vertical movement and a receding movement in thedirection of movement of the work as the same is fed to the saw, andmeans operative at will actuated by an upward movement of said guardplate for locking the same in different vertical adjustments.

3. A guard of the kind described comprising a hood made up of arelatively fixed arch plate and a relatively movable guard plate,connections, including a lifting plate, supporting said guard plate fromsaid arch plate, for vertical movement and areceding movement in thedirection of movement of the work as the same is fed to the saw, andmeans operative at will actuated by an upward movement of said guardplate for locking the same in different vertical adjustments, but withfreedom for further upward movement away from the saw.

4. A guard of the kind described comprising a hood made up of arelatively fixed arch plate and a relatively movable guard plate,connections, including a lifting plate, supporting said guard plate fromsaid arch plate, for vertical movement and a receding movement in thedirection of movement of the work as the same is fed to the saw, and apair of reversely acting one-way locks, operative at will, one of whichis actuated by a lifting movement of said guard plate operative, atwill, for locking said guard plate in different vertical adjustments inrespect to said arch plate.

A guard of the kind described comprising a hood made up of a relativelyfixed arch plate and a relatively movable guard plate, connections,including a lifting plate,

supporting said guard plate from said arch plate .for vertical movementand a receding movement in the dlrection of movement of the work as thesame is fed to the saw, and automatic means, operative under a forwardlifting movement, of said guard plate, for locking the same againstupward movement.

6. A guard of the kind described comprising a hood made up of arelatively fixed arch plate and a relatively movable guard plate,connections, including a lifting plate, supporting said guard plate fromsaid arch plate,-for vertical movement and a receding movement in thedirection of movement of the work as the same is fed to the saw, and apawl and ratchet device actuated by an upward lifting movement of saidguard plate, operative at Will for locking the same in different furtherupward adjustments but with freedom for vertical movement away from thesaw.

7. A guard of the kind described comprising a hood made up of arelatively fixed arch plate and a relatively movable guard plate,connections, including a lifting plate, supporting said guard plate fromsaid arch plate, for vertical movement and a receding movement in thedirection of movement of the work as the same is fed to the saw, and apair of reversely acting pawl and ratchet devices for locking said guardplate in different vertical adjustments, one of said pawl and ratchetdevices being arranged to be actuated by an upward lifting movement ofsaid guard plate.

8. A guard of the kind described; comprising a hood made up of arelatively fixed arch plate and a relatively movable guard plate,connections, including a link, supporting said guard plate from saidarch plate,-

for vertical movement and a receding movement in the direction ofmovement of the work as the same is fed to the saw, said link having alimited endwise movement for shortening its operative length under anend thrust thereon, and automatic means rendered operative under theshortening action of said link, to lock said guard plate against upwardmovement.

9. A guard of the kind described comprising a hood made up of arelatively fixed arch plate and a relatively movable guard plate,connections, including a lifting plate and a link, supporting,respectively, the frontand rear ends of said guard plate from said archplate, for vertical movement and for receding movement in the directionof movement of the work as the same is fed to the saw, said link havinga limited endwise movement for shortening its operative length under anend thrust thereon, auto matic means rendered operative under theshortening action of said link, to lock said guard plate against upwardmovement, and a pawl and ratchet device for locking said guard-plate=in. differentvertical adjust ments but with freedom for verticalmovement away from said saw.

10. The combination With a Work table and a support thereabove, of ahood made a up of an arch plate and a guard plate, said arch plate beingmounted on said support for angular adjustment in the plane of the saw,and said guard plate being supported from said arch plate for verticalswinging Copies of this patent may be obtained for five cents each, byaddressing the Commissioner of Patents,

Washington, D. C."

